From the onset of computer technology, it has been a design goal to create a powerful computer with the least amount of space. In this endeavor, integrated circuitry together with state-of-the-art manufacturing and attachment techniques has considerably reduced the overall packaging space of computers.
To increase the power of a computer in terms of memory capacity and speed, it is necessary to add integrated circuits and/or discrete devices. These devices are usually attached to printed circuit boards. Because of the limited space available in the original design, it is difficult to find space within a computer to add additional boards. Therefore, if an expansion slot is not available or a slot is available but without sufficient room, a separate structure with the required card(s) must be used and connected to the computer by means of an external connector cable.
One of the prime elements that is currently used to increase computer memory capacity is a hard disk drive. These drives are used in combination with a controller card and are typically much larger in terms of bulk than a set of printed circuit boards. Therefore, because of its size, the drive is typically inserted into a dedicated front slot on the computer. The placement of the drive within the computer is difficult in terms of finding space and making electrical connections.